Entry fittings are used in underground sumps to seal the interface between an access opening of the sump and a pipe extending into the sump through the access opening. Entry fittings are designed to prevent the flow of a fluid, such as gasoline, which has leaked into the sump, from entering the surrounding ground, and for preventing the flow of ground water into the sump.
An underground sump can require one or more such entry fittings depending upon the number of fuel conduits entering and exiting the sump. Access openings are usually formed in the sump at the installation site. Due to varying conditions in the field, and of the sump itself, an access opening can sometimes be out-of-round, or have an irregular shape. Conventional entry fittings, however, have a relatively fixed or small range of sealing force, and will only properly seal when used with an access opening that has a regular shape, and also a certain diameter. Thus, if an irregular access opening is formed in a sump, or the diameter is slightly larger than specified for the particular entry fitting size, either a larger hole must be formed and a larger entry fitting utilized, or the sump must be discarded.
After an entry fitting has been initially installed, the seal eventually ages and takes a compression set. Slight movement of the pipe or thermal expansion and contraction can result in leakage about the seal. When this occurs, conventional entry fittings must be entirely replaced due to the lack of or the relatively small range of adjustable sealing force provided by such entry fittings.
There are several conventional entry fitting designs in use. One such entry fitting includes a rubber boot have a planar portion and a tubular portion, the tubular portion being conjoint with and perpendicular to the planar portion. The planar portion is positioned on the exterior of the sump wall and contains bolts which extend through a plurality of holes drilled in the sump and through a compression ring positioned on the interior of the sump wall. Nuts threadedly engage the bolts and pull the planar portion against the exterior of the sump wall. The tubular portion extends into the sump through the access opening, and is sealingly clamped to the pipe. This type of entry fitting does not allow a range of adjustable sealing force between the planar portion and the sump wall, and requires considerable installation time due to the required drilling of holes, and tightening of the requisite nuts and bolts. Further, if the boot develops a leak, the entire entry fitting must be replaced, since there is not a separate seal separable from the entry fitting. Further, replacement of the entry fitting may necessitate removal of backfill from the exterior of the sump to permit withdrawal and replacement of the boot.
Another conventional entry fitting currently in use includes a boot which is positioned in the access opening, and a rigid plastic insert which is forced into the boot to be concentric with the access opening and radially urge the boot against the edge of the access opening. However, the rigid plastic insert has a predetermined size, and thus the boot and insert require a fairly specific size opening. Further, if the boot develops a leak, the entire boot must be replaced as there is no mechanism for increasing the radial force exerted by the plastic insert.
It is apparent that an entry fitting which achieves an increased range of adjustable sealing force and allows flexibility in the size and shape of access openings in which it can be used, which allows replacement of a relatively inexpensive seal without replacement of the entire entry fitting, and which can be replaced without requiring removal of backfill from the exterior of the sump would be desirable.